The best way to do it is to creat two partitions on one drive, and an os on each partition. Or if you have two drives, one os on each, and just change in your bios which drive you want to boot off of. There is hard ware I have seen on tigerdirect.com, it goes in your 5.25 bay and you can have 3 os instaled on three drives. Check them out and see which one is best for you.